Low power audio detection

Abstract

Devices and methods of detecting a predetermined audio signal in audio signals are provided. A device includes a processor coupled to a clock signal generator, a power controller and an audio detector. The power controller controls a clock rate provided to the processor by the clock signal generator, to control the device to operate in a low power mode having a relatively low power consumption or in a normal power mode having a relatively high power consumption. The audio detector receives audio signals and detects, in the low power mode, probable presence of a predetermined audio signal in the audio signals. The power controller controls the device to switch from the low power mode to the normal power mode responsive to the detected presence of the predetermined audio signal by the audio detector.

What is claimed: 
     
       1. A method, performed by a device, of detecting an audio signal of interest in a number of audio signals, the method comprising:
 operating the device in a low power mode having a relatively low power consumption; 
 detecting, in the low power mode, a probable presence of the audio signal of interest by:
 filtering, using a filter bank, the number of audio signals to include only frequencies corresponding to the audio signal of interest; 
 detecting, using a narrowband signal detector and a wideband signal detector, variations in the filtered audio signals over a narrow bandwidth and a wide bandwidth, respectively; and 
 comparing, using a pattern comparator, the detected variations in the filtered audio signals with frequency characteristics of a comparison signal; and 
 
 switching the device from the low power mode to a normal power mode based on the detected probable presence of the audio signal of interest, the normal power mode having a relatively high power consumption. 
 
     
     
       2. The method of  claim 1 , wherein the audio signal of interest includes a voice signal. 
     
     
       3. The method of  claim 1 , further comprising:
 storing at least a portion of the number of audio signals based on detection of the probable presence of the audio signal of interest. 
 
     
     
       4. The method of  claim 1 , wherein detecting the probable presence of the audio signal of interest is performed with a first detection accuracy, the method further comprising:
 further detecting the probable presence of the audio signal of interest with a second detection accuracy that is higher than the first detection accuracy, the device being switched from the low power mode to the normal power mode based on the further detected presence of the audio signal of interest. 
 
     
     
       5. The method of  claim 4 , wherein the further detecting of the probable presence of the audio signal of interest is performed in the low power mode. 
     
     
       6. The method of  claim 4 , wherein the further detecting of the probable presence of the audio signal of interest is performed with a higher clock rate than a clock rate associated with the low power mode. 
     
     
       7. The method of  claim 1 , further comprising:
 prior to detecting of the probable presence of the audio signal of interest, applying at least one filter having a filter characteristic to the number of audio signals. 
 
     
     
       8. The method of  claim 1 , further comprising:
 prior to detecting the probable presence of the audio signal of interest: 
 determining a level of the number of audio signals; 
 comparing the level to a threshold; and 
 when the level is greater than the threshold, performing the detecting of the probable presence of the audio signal of interest. 
 
     
     
       9. The method of  claim 1 , wherein detecting the probable presence of the audio signal of interest includes:
 detecting a pattern in the number of audio signals; and 
 comparing the detected pattern to the audio signal of interest. 
 
     
     
       10. The method of  claim 9 , wherein detecting the pattern includes monitoring a variation in at least one frequency of the number of audio signals over time, the at least one frequency associated with the audio signal of interest. 
     
     
       11. The method of  claim 1 , further comprising:
 determining an accuracy of the detection of the probable presence of the audio signal of interest; and 
 adjusting at least one parameter for detecting the probable presence of the audio signal of interest based on the determined accuracy. 
 
     
     
       12. A device comprising:
 a processor coupled to a clock signal generator; 
 a power controller configured to operate the device in a low power mode having a relatively low power consumption or in a normal power mode having a relatively high power consumption; and 
 an audio detector, coupled to the power controller, and configured to detect, in the low power mode, a probable presence of an audio signal of interest in a number of audio signals, the audio detector comprising:
 a filter bank configured to filter the number of audio signals to include only frequencies corresponding to the audio signal of interest; 
 a narrowband signal detector configured to detect variations in the filtered audio signals over a narrow bandwidth; 
 a wideband signal detector configured to detect variations in the filtered audio signals over a wide bandwidth; and 
 a pattern detector configured to compare the detected variations in the filtered audio signals with frequency characteristics of a comparison signal, wherein the power controller is further configured to switch the device from the low power mode to the normal power mode based on the detected probable presence of the audio signal of interest. 
 
 
     
     
       13. The device of  claim 12 , wherein the audio signal of interest includes a voice signal. 
     
     
       14. The device of  claim 12 , further including a storage device for storing at least a portion of the number of audio signals. 
     
     
       15. The device of  claim 12 , wherein the audio detector is configured to detect the probable presence of the audio signal of interest with two or more different detection accuracies. 
     
     
       16. The device of  claim 12 , wherein the audio detector is included in the processor. 
     
     
       17. The device of  claim 12 , wherein the audio detector is separate from the processor. 
     
     
       18. The device of  claim 12 , further comprising a digital signal processor (DSP) coupled to the clock signal generator, the DSP configured to further detect the probable presence of the audio signal of interest with a higher detection accuracy than the audio detector. 
     
     
       19. The device of  claim 12 , wherein the audio detector includes at least one filter having a filter characteristic to filter the number of audio signals. 
     
     
       20. The device of  claim 12 , wherein the audio detector includes a level trigger to compare a level of the number of audio signals to a threshold. 
     
     
       21. The device of  claim 12 , wherein the audio detector includes a comparator configured to detect a pattern in the number of audio signals and to compare the detected pattern to the audio signal of interest. 
     
     
       22. The device of  claim 21 , wherein the comparator is configured to monitor a variation in at least one frequency of the number of audio signals over time, the at least one frequency associated with the audio signal of interest. 
     
     
       23. The device of  claim 12 , further comprising a microphone configured to capture the number of audio signals. 
     
     
       24. The device of  claim 12 , wherein the device is configured to adjust at least one parameter of the audio detector. 
     
     
       25. The device of  claim 24 , wherein the at least one parameter is adjusted based on at least one of a detection accuracy of a detection result of the audio detector, a noise condition, or a new audio signal of interest. 
     
     
       26. The method of  claim 1 , wherein the audio signal of interest includes a non-voice audio signal that is at least one member of the group consisting of a whistle, a clap, and a click. 
     
     
       27. The method of  claim 2 , wherein the voice signal is at least one member of the group consisting of a user's voice, a set of user voices, and one or more keywords. 
     
     
       28. The device of  claim 12 , wherein the audio signal of interest includes a non-voice audio signal that is at least one member of the group consisting of a whistle, a clap, and a click. 
     
     
       29. The device of  claim 13 , wherein the voice signal is at least one member of the group consisting of a user's voice, a set of user voices, and one or more keywords.